The present invention relates to connectors for active implantable medical devices. Although the invention is mainly described in the context of connectors for pacemakers, it should be understood that this is only one embodiment of the invention. The invention is applicable more generally to a wide variety of xe2x80x9cactive implantable medical devicesxe2x80x9d as such devices are defined by the Jun. 20, 1990 Director No. 90/385/CE of the Council of the European Communities. This definition of active implantable medical devices includes, in addition to pacemakers, defibrillators and/or cardiovertors, neurological devices, diffusion pumps delivering medical substances, cochlear implants, implanted biological sensors, etc.
Active implantable medical devices typically comprise a case, also called a housing, containing the electronics of the devices. In the case of cardiac devices, the case is generally referred to as a xe2x80x9cgeneratorxe2x80x9d or xe2x80x9cpulse generatorxe2x80x9d. The electronics inside the case are electrically and mechanically connected to one or more probes exterior to the case.
More specifically, the device case has a body containing the various electronic circuits and a power supply for the device, and a connector head that is fixed to the case and equipped with one or more cavities able to receive one or more probes.
In this regard, reference can be made to the French and European standard NF EN 50007 entitled xe2x80x9cConnector with Low Profile for Implantable Pacemakerxe2x80x9d, which defines a standardized connection known as xe2x80x9cIS-1xe2x80x9d. This standard makes it possible to guarantee the interchangeability of the probes and the pulse generators respectively produced by numerous different manufacturers. As noted, the invention is not intended to be limited to the particular case of the connection systems according to this standard, nor even to the case of connection systems for pacemakers.
Usually, the connection between a probe and the connector head of the generator is carried out by one or more screws, tightened by the surgeon using an ad hoc tool, such as a screwdriver provided with a torque limiter. The connection is made at the time of implantation.
However, forming the connection by tightening a screw presents several disadvantages. First, in addition to requiring provision of a specific tool for this purpose, this known technique also requires the presence of a plug that permits the passage of the tool through the plug in a close frictional fit. This is so that after the end of the probe is inserted in the connector cavity, the screw is tightened and the tool is withdrawn, the plug reseals to prevent the head from coming into contact with organic fluids. This requirement that the plug be penetrable to permit the tool to enter for tightening the screw and then reseal after removal of the tool presents an additional cost of manufacture and an increase in the volume of the generator with respect to the size of the connector head.
Second, this known connection system suffers from a risk that the surgeon will not tighten the screw properly, and either tighten the screw too much and damage the device or insufficiently tighten the screw, thus leaving the probe at risk of disconnecting. The point of proper tightening is all the more critical since there is no visual means to verify that the tightening has been correctly performed.
The disadvantages of this known connection system are particularly amplified in the case of implantable devices using a large number of probes, for example, three, four, and even more probes, as in the case of the so-called enslaved (rate responsive) devices requiring an external physiological sensor(s), and xe2x80x9ctriple chamberxe2x80x9d, xe2x80x9cquadruple chamberxe2x80x9d and xe2x80x9cmultisitexe2x80x9d cardiac devices requiring the implantation, and thus connection, of detection and/or stimulation electrodes in several locations of the myocardium. These known sensors, detection electrodes and stimulation electrodes are types of probes as the term xe2x80x9cprobexe2x80x9d is used herein.
Thus, an implant designed to receive four probes would include eight screws, which implies, on a mechanical level, a bulky and complex structure for the connector head. Moreover, the structure is rather delicate to use. For example, at the time of the implantation, the surgeon must tighten all eight screws properly, without undertightening or overtightening of same.
It is, therefore, an object of the invention to overcome the various disadvantages of the known connection systems by providing an improved connection system having a connector head structure that is simple to manufacture and easy to use by the practitioner.
More particularly, the invention is useable as part of an implantable active medical device of the generic type, including a generator and a connector head equipped with a plurality of parallel axial cavities receiving respective probes, more specifically a connector component of the probe which may be in the form of an electrically conductive cylindrical pin, and reversible means for tightening mechanically each probe connector head within its cavity in the connector head.
Broadly speaking, according to the invention, the means for tightening mechanically includes retractable elements actuated simultaneously by a common action element movable between two positions, one locked and the other unlocked. In the locked position, the retractable elements project inside each respective cavity to exert a contact pressure, preferably radially project to exert a radial contact pressure, on each probe connector component inserted into its respective cavity. In the unlocked position, the probe connector may pass unobstructedly into and out of its corresponding cavity.
In the case that the probe connector components are of the type which comprise an electrically insulated area adjacent an annular cylindrical conducting element, or interposed between two cylindrical conducting elements, in which examples the insulating sheath and the conducting elements are preferably annular cylindrical lengths, the retractable elements preferentially exert a radial pressure on the electrically insulated area. Similarly, if more than one electrically insulated area exists, multiple retractable elements exerting pressure on one or more of the insulating areas can be used.
In a preferred embodiment, the probe connector component includes a sealing element (also called a sealing relief) protruding from the annular surface which engages the connector head cavity to form a seal, and the retractable elements project into an area of the probe which is distal to the sealing relief. More than one sealing relief can be used.
In one advantageous embodiment of the connector system, the axial female cavities are distributed regularly about and at the same distance from a central axis of the connector head, the central axis being parallel to the axes of the cavities. In this embodiment, the retractable elements are carried by a common barrel that is movable around the central axis. The retractable elements are advantageously made out of an elastically deformable material, for example, a silicone.